Characteristics and outcomes of therapy-related APL after different front-line therapies

Background

Information on the true incidence of therapy-related acute promyelocytic leukemia (t-APL) is scarce. However, the incidence appears to have increased in recent years, with some studies suggesting that the outcomes are similar to patients with de novo APL.1 The combined regimen of arsenic trioxide (ATO) and all-trans retinoic acid (ATRA) is effective in de novo low- to intermediate-risk APL, but it has not been evaluated in a large cohort of patients with t-APL.2 At the 7th International Symposium on APL, Kayser and colleagues presented an analysis of outcomes in patients with t-APL according to different treatment strategies.3

Study design

A total of 103 patients with APL were retrospectively studied.

The patients had been treated between 1991 and 2015 across 11 study groups/institutions in the U.S. and Europe.

A total of 87 (84%) patients had solid cancer (breast: 38, prostate: 14, head and neck: 9, gastrointestinal: 9, and other: 14).

Five patients had non-Hodgkin lymphoma, while three had Hodgkin lymphoma.

Eight patients had autoimmune disease.

The median latency period from prior disease to the onset of t-APL was 3.5 years (range: 0.4–26.2).

Table 1. Baseline characteristics

Efficacy

Patients receiving ATO/ATRA had the highest complete remission rate at 100%, while patients received ATRA only had the highest early death rate at 43%. (Table 2)

The patients receiving CTX/ATRA had the highest number of competing events in remission.

Two had relapses of the prior malignancy, two had infections, two had therapy-related acute myeloid leukemia, three had relapses of t-APL, one developed diffuse large B-cell lymphoma, and one had a competing event of unknown cause.

Of the patients receiving ATO/ATRA, one patient had relapse of the prior malignancy, one patient had an infection, and one suffered cardiopulmonary arrest during therapy.

One patient receiving CTX/ATO/ATRA and three receiving ATRA had relapses of the prior malignancy.